1. Field of the Invention
The present invention relates to a cooling device for effectively cooling an electronic elements producing concentrated heat, such as a CPU, which is employed to a portable electronic device having few space to conduct and radiate the concentrated heat, such as a notebook PC, and a portable electronic device to which the cooling device is installed with an effective configuration.
2. Description of the Related Art
As technology has increased a capacity of electronic elements, it has been found that the amount of produced heat has increased significantly. Though the amount of the heat is in a range of several Watts to several tens Watts, it is far from easy to radiate the heat because the heat is generated in a concentrated manner, for example, it is generated at an area of 1 square centimeter or such. The problem of the concentrated heat comes to be more significant in a case of portable electronic devices, such as a notebook PC, because the portable electronic devices do not have enough space to equip a large cooling fan and a large heat sink.
As a device to effectively radiate the concentrated heat, there is proposed a heat radiation module having an air flow duct and a cooling fan housed therein, which covers a heat sink fixed to a CPU so as to flow relatively strong wind onto the heat sink. The heat radiation module effectively cools the CPU which is the most concentrated heat source in a notebook PC. However, if a heat value of CPU is increased, the heat sink and the cooling fan must be made larger and a rotation speed of the cooling fan must be higher. There is a definite limitation to provide a large heat sink and a large cooling fan with the notebook PC because the notebook PC is lack of a marginal space therein. Further, a severe noise generation caused by the high-speed cooling fan should be avoided because the notebook PC is usually used in a calm space.
Japanese Patent Applications Laid-Open No. 10-254583, No. 9-145273, No. 11-340671 and No. 8-42983 disclose cooling systems for a notebook PC, in which a heat pipe is employed. Japanese Patent Application Laid-Open No. 7-142886 discloses a cooling system for a notebook PC including a flexible tube and a pump for circulation of a liquid coolant.